Evaluation of different total Leishmania amazonensis antigens for the development of a first-generation vaccine formulated with a Toll-like receptor-3 agonist to prevent cutaneous leishmaniasis

BACKGROUND Unfortunately, no any vaccine against leishmaniasis has been developed for human use. Therefore, a vaccine based on total Leishmania antigens could be a good and economic approach; and there are different methodologies to obtain these antigens. However, it is unknown whether the method to obtain the antigens affects the integrity and immune response caused by them. OBJECTIVES to compare the protein profile and immune response generated by total L. amazonensis antigens (TLA) produced by different methods, as well as to analyse the immune response and protection by a first-generation vaccine formulated with sonicated TLA (sTLA) and polyinosinic:polycytidylic acid [Poly (I:C)]. METHODS TLA were obtained by four different methodologies and their integrity and immune response were evaluated. Finally, sTLA was formulated with Poly (I:C) and their protective immune response was measured. FINDINGS sTLA presented a conserved protein profile and induced a strong immune response. In addition, Poly (I:C) improved the immune response generated by sTLA. Finally, sTLA + Poly (I:C) formulation provided partial protection against L. amazonensis infection. MAIN CONCLUSIONS The protein profile and immune response depend on the methodology used to obtain the antigens. Also, the formulation sTLA + Poly (I:C) provides partial protection against cutaneous leishmaniasis in mice.

Disseminated leishmaniasis: clinical, pathogenic, and therapeutic aspects

Abstract: Disseminated leishmaniasis is a severe and emerging form of American tegumentary leishmaniasis. Disseminated leishmaniasis is defined by the presence of more than 10 polymorphic cutaneous lesions, distributed over more than two noncontiguous parts of the body. Nasal mucosal involvement is observed in almost half of cases. Disseminated leishmaniasis patients present with a decreased production of Th1 cytokines in the peripheral blood due to the attraction of leishmania- activated T cells to the multiple cutaneous lesions. Disseminated leishmaniasis development is poorly understood and is related to a complex network involving environmental, host immune response, and parasite factors, in which L. braziliensis polymorphism plays an important role. Disseminated leishmaniasis is a challenging disease to cure, presenting a high failure rate of 75% to pentavalent antimony therapy. Despite its importance and severity, this form of American tegumentary leishmaniasis has been poorly studied and documented, deserving greater attention from professionals working in endemic areas.

Clinico-immunological spectrum of American tegumentary leishmaniasis and leprosy coinfection: A case series in Southeastern Brazil

Abstract INTRODUCTION: American tegumentary leishmaniasis (ATL) and leprosy share common areas of prevalence, but reports of coinfection are scarce. METHODS: We report a series of 9 ATL-leprosy cases and discuss the association. An integrative diagram to analyze the clinico-immunological features of coinfection with both diseases. RESULTS: Nine patients with leishmaniasis (5 cutaneous, 3 mucocutaneous, 1 disseminated case) exhibited concurrent infection with distinct clinical forms of leprosy. Our diagram-based analysis evidenced a divergent clinico-immunological spectrum for each disease in 8 out of 9 cases. CONCLUSIONS: The spectrum of ATL-leprosy comorbidity suggests that the host has a specific immune response against each pathogen.

Cytotoxic activity in cutaneous leishmaniasis

Cutaneous leishmaniasis (CL) is a chronic disease caused by species of the protozoan Leishmania and characterised by the presence of ulcerated skin lesions. Both parasite and host factors affect the clinical presentation of the disease. The development of skin ulcers in CL is associated with an inflammatory response mediated by cells that control parasite growth but also contribute to pathogenesis. CD8+ T cells contribute to deleterious inflammatory responses in patients with CL through cytotoxic mechanisms. In addition, natural killer cells also limit Leishmania infections by production of interferon-γ and cytotoxicity. In this review, we focus on studies of cytotoxicity in CL and its contribution to the pathogenesis of this disease.

Maxadilan-simile expression in Nyssomyia neivai, a sandfly vector in an endemic region of Brazil, and its immunogenicity in patients with American tegumentary leishmaniasis

BACKGROUND Maxadilan (Max) is a salivary component in the sandfly Lutzomyia longipalpis (Lutz & Neiva 1912), a vector of visceral leishmaniasis. Max has a powerful vasodilatory effect and is a candidate vaccine that has been tested in experimental leishmaniasis. Nyssomyia neivai (Pinto 1926) is a vector of the pathogen responsible for American tegumentary leishmaniasis (ATL) in Brazil. OBJECTIVE We searched for Max expression in Ny. neivai and for antibodies against Max in ATL patients. METHODS cDNA and protein were extracted from the cephalic segment, including salivary glands, of Ny. neivai and analysed by polymerase chain reaction, DNA sequencing, and blotting assays. The results were compared with data obtained from Lu. longipalpis samples. We quantified antibodies against Max in serum samples from 41 patients with ATL (31 and 10 with the cutaneous and mucocutaneous forms, respectively) and 63 controls from the endemic northeastern region of São Paulo state, using enzyme-linked immunosorbent assay. FINDINGS Recognition of a Max-simile peptide by specific antibodies confirmed expression of a Max sequence in Ny. neivai (GenBank EF601123.1). Compared to controls, patients with ATL presented higher levels of antibodies against Max (p = 0.004); 24.4% of the patients with ATL and 3.2% of the controls presented anti-Max levels above the cutoff index (p = 0.014). The anti-Max levels were not associated with the specific clinical form of ATL, leishmanin skin test response, absence or presence of amastigotes in histopathologic exam, results of indirect immunofluorescence testing for leishmaniasis, or duration of cutaneous form disease. MAIN CONCLUSION High serum anti-Max levels did not protect patients against ATL, but confirmed previous natural exposure to Ny. neivai bites in this ATL endemic region.

Asymptomatic infection with American cutaneous leishmaniasis: epidemiological and immunological studies

American cutaneous leishmaniasis (ACL) is a major public health problem caused by vector-borne protozoan intracellular parasites from the genus Leishmania, subgenera Viannia and Leishmania. Asymptomatic infection is the most common outcome after Leishmania inoculation. There is incomplete knowledge of the biological processes explaining the absence of signs or symptoms in most cases while other cases present a variety of clinical findings. Most studies of asymptomatic infection have been conducted in areas of endemic visceral leishmaniasis. In contrast, asymptomatic ACL infection has been neglected. This review is focused on the following: (1) epidemiological studies supporting the existence of asymptomatic ACL infection and (2) immunological studies conducted to understand the mechanisms responsible for controlling the parasite and avoiding tissue damage.

T-cell receptor Vβ repertoire of CD8+ T-lymphocyte subpopulations in cutaneous leishmaniasis patients from the state of Rio de Janeiro, Brazil

In human cutaneous leishmaniasis (CL), the immune response is mainly mediated by T-cells. The role of CD8⁺ T-lymphocytes, which are related to healing or deleterious functions, in affecting clinical outcome is controversial. The aim of this study was to evaluate T-cell receptor diversity in late-differentiated effector (LDE) and memory CD8⁺ T-cell subsets in order to create a profile of specific clones engaged in deleterious or protective CL immune responses. Healthy subjects, patients with active disease (PAD) and clinically cured patients were enrolled in the study. Total CD8⁺ T-lymphocytes showed a disturbance in the expression of the Vβ2, Vβ9, Vβ13.2, Vβ18 and Vβ23 families. The analyses of CD8⁺T-lymphocyte subsets showed high frequencies of LDE CD8⁺T-lymphocytes expressing Vβ12 and Vβ22 in PAD, as well as effector-memory CD8⁺ T-cells expressing Vβ22. We also observed low frequencies of effector and central-memory CD8⁺ T-cells expressing Vβ2 in PAD, which correlated with a greater lesion size. Particular Vβ expansions point to CD8⁺ T-cell clones that are selected during CL immune responses, suggesting that CD8⁺ T-lymphocytes expressing Vβ12 or Vβ22 are involved in a LDE response and that Vβ2 contractions in memory CD8⁺T-cells are associated with larger lesions.

Identification and glycobiological characterization of circulating immune complexes in patients with visceral leishmaniasis and post kala azar dermal leishmaniasis.

Here, we investigated the quantitative and qualitative differences in antibody classes and subclasses in serum immune complexes (ICs) of Visceral Leishmaniasis (VL), Post Kala-azar Dermal Leishmaniasis (PKDL) and different cross reactive diseases like Malaria, Leprosy, Vitiligo as compared to control subjects. IC levels were measured through a newly developed PEG ELISA, using L. donovani promastigote membrane antigen coated plate. Antibody classes and subclasses were identified using polyspecific sera and monoclonal antibodies, respectively. ICs were purified using polyethylene glycol (PEG) precipitation. Conditional logistic regression showed an association between IgG1-containing ICs and increased risk of PKDL (OR=75, P <0.05) and an association of IgG-containing ICs with VL (OR=621, P=0.001). PEG ELISA demonstrated almost 13-15 fold higher IgG containing ICs titers in VL as compared to control (P <0.001). The assay further established a significant (P <0.05) difference in the IgG containing ICs titers between VL and PKDL. The isolated ICs were further analyzed by subjecting them to one-dimensional PAGE and subsequently stained with combination of periodic acid schiff (PAS) with silver. A differential banding pattern between VL and PKDL was obtained. Four distinct bands with carbohydrate rich glycoconjugates were identified in PKDL ICs, which were absent in VL and control group. It suggests the scope for developing a novel differential diagnostic assay.

Post-kala-azar dermal Leishmaniasis in two different clinical contexts

In Brazil, visceral Leishmaniasis is caused by Leishmania chagasi. The development of cutaneous lesions in visceral leishmaniasis patients has been described in two different clinical contexts. Patients with compromised immunity can develop skin lesions as a direct consequence of a current visceral disease. Equally, patients with a history of kala-azar and progressive, immune improvement occasionally develop skin lesions as a consequence of immune reconstitution infl ammatory syndrome. These cases manifest in similar fashion to the classic form of post-kala-azar dermal Leishmaniasis. We describe different cases that exemplify these two clinical presentations.

Consumo de cafeína durante a gestação e transtorno de déficit de atenção e hiperatividade (TDAH): uma revisão sistemática da literatura / Caffeine consumption during pregnancy and attention deficit hyperactivity disorder (ADHD): a systematic literature review / Consumo de cafeína durante el embarazo y trastorno por déficit de atención e hiperactividad (TDAH): una revisión sistemática de la literatura

O objetivo do presente estudo foi avaliar, mediante revisão sistemática da literatura, as evidências acerca da associação entre consumo materno de cafeína durante a gestação e transtorno de déficit de atenção e hiperatividade (TDAH) na infância. A busca na literatura ocorreu de forma sistemática, em múltiplas etapas, nas bases PubMed, LILACS, BIREME e PsycINFO, com limites para artigos publicados em português, inglês e espanhol, realizados em humanos. Foram encontradas 373 referências. Dessas, somente cinco foram mantidas, por atenderem ao objetivo deste estudo. Os cinco trabalhos foram realizados em países desenvolvidos; a maioria utilizou delineamento longitudinal e foi publicada nos últimos cinco anos. Apenas um estudo encontrou associação positiva. Estudos sobre o consumo de cafeína na gestação e TDAH são escassos, com resultados controversos e se deparam com várias dificuldades metodológicas, como falta de padronização na definição do desfecho.

This aim of this study was to conduct a systematic literature review on the association between maternal caffeine intake during pregnancy and attention deficit hyperactivity disorder (ADHD) in childhood. The systematic multiple-stage literature search in PubMed, LILACS, BIREME, and PsycINFO was limited to research in human subjects and published in Portuguese, English, and Spanish. A total of 373 references were retrieved. Of these, only five met the study's objectives and were kept in the review. Most of the studies employed a longitudinal design, were conducted in developed countries, and were published in the last five years. Only one study found a positive association. Studies on caffeine consumption during pregnancy and ADHD are scarce, with conflicting results and several methodological difficulties such as lack of standardized outcome measures.

El objetivo de este estudio fue evaluar, a través de una revisión sistemática de la literatura, evidencias sobre la asociación entre el consumo de cafeína durante el embarazo y el trastorno por déficit de atención e hiperactividad (TDAH) en la infancia. Se realizó una búsqueda sistemática en la literatura, por etapas múltiples, en PubMed, LILACS BIREME y PsycINFO, limitándose a artículos publicados en portugués, inglés y español, realizados en estudios sobre humanos. Fueron localizadas 373 referencias. De ellas, apenas se mantuvieron cinco, por cumplir el objetivo de este estudio. Los estudios se realizaron en países desarrollados; el diseño longitudinal fue el más utilizado y se trata de publicaciones de los últimos cinco años. Sólo un estudio encontró asociación positiva. Los estudios sobre el consumo de cafeína durante el embarazo y el TDAH son escasos, con resultados controvertidos, y enfrentan varias dificultades metodológicas, como la no estandarización de la evaluación del resultado.

Estudo clínico, epidemiológico e imunológico para leishmaniose tegumentar americana em centro de referência em dermatologia / Clinical, epidemiological and immunological study to american tegumentary leishmaniasis in a dermatology reference center

Leishmaniose Tegumentar Americana (LTA) é uma doença infecciosa, causada por protozoários do gênero Leishmania. É uma das doenças infectoparasitárias mais incidentes no mundo. No presente trabalho realizou-se um estudo transversal retrospectivo das características clínicas, epidemiológicas e imunológicas de portadores de Leishmaniose Tegumentar Americana.Foram utilizados prontuários de 34 pacientes com diagnóstico de LTA. A análise estatística foi realizada pelo Teste de Spearman. O sexo masculino foi acometido em 68% e o feminino 32%. A idade variou de 1 a 92 anos. A forma cutânea localizada ocorreu em 79,5%,sendo as úlceras a forma clínica mais comum (56%).Principal área acometida foi face (44%). O tempo para o diagnóstico foi menor que 10 meses em 68% dos indivíduos.Intradermorreação de Montenegro (IDRM) foi realizada em 29 pacientes, com positividade em 89,6% e a imunofluorescência indireta (IFI) em apenas 16 pacientes, sendo positiva em 13. A idade e o tempode evolução da doença apresentaram associação significativa com IDRM. Entretanto não foi observada associação da IFI com a idade do paciente e o tempo de doença, pelo teste de Spearman. O tratamento foi realizado na maioria dos casos com glucantime (71%),seguido de pentamidina (17%). Os resultados evidenciam que os exames sorológicos constituem uma ferramenta auxiliar e a correlação com achados clínicos e histopatológicos são imprescindíveis.

Introduction: American cutaneous leishmaniasis (ACL) is an infectious disease caused by protozoa of the genus Leishmania. World  leishmaniasis  is an important endemic disease and public health problem in developing countries. Methods: We conducted a retrospective, descriptive and analytical cross-sectional study of 34 patients diagnosed with ACL. Statistical analysis was performed using the nonparametric Spearman’s test. Results: The gender involved was male (68%) and female(32%); the age range of 1 to 92 years old. The most common clinical manifestations were localized cutaneous form (79.5%) and the ulcers (56%).The face was main affected area (44%) and the minor time from onset of symptoms to consultation was 10 months (68%) of patients. Montenegro skin test (MST) was performed in 29 patients, being positive in (89.6%) and the indirect immunofluorescence (IIF) in only 16 patients, being positive in 13. The age and the duration of the disease were significantly associated with MST. Conclusions: It was not observed the IFI association with the patient’s age and disease duration. The treatment was in most cases, meglumine antimoniate (71%), followed Pentamidine (17%). The results demonstrated thatthe serological tests constitute an auxiliary tool andthe correlations with clinical and histopathological findings are essential.

Genética da leishmaniose cutânea em humanos: identificação de vias imunológicas que contribuem para a suscetibilidade à doença / Genetics of cutaneous leishmaniasis in humans: identification of immunological pathways that contribute to disease susceptibility

A leishmaniose cutânea (LC) é a forma clínica mais comum do complexo de doenças causadas por protozoários do gênero Leishmania. Interessantemente, alguns indivíduos infectados com espécies dermotrópicas do parasito não desenvolvem a LC, enquanto outros desenvolvem lesões crônicas. Os mecanismos envolvidos nesta variação permanecem amplamente desconhecidos, embora fatores genéticos do hospedeiro podem influenciar o risco de desenvolver a doença. No primeiro estudo apresentado nesta tese, foi mostrado que a sinalização IL-2/IL-2R desempenha um papel crucial na resposta imune contra espécies dermotrópicas de Leishmania. Os transcritos de vários genes da via de sinalização IL-2 são mais abundantes em úlceras cutâneas causadas por Leishmania braziliensis do que em amostras de pele normal de dadores não infectados. Um estudo de associação em famílias brasileiras (209 famílias nucleares) identificou dois polimorfismos no gene IL2RA associados à LC causada por L. braziliensis [rs10905669 (p = 3x10-4) e rs706778 (p = 3x10-4)]...

Cutaneous leishmaniasis (CL) is the most common clinical form of leishmaniasis and can be caused by several dermotropic Leishmania species. Interestingly, some infected individuals do not develop cutaneous lesions, while others are severely affected. The basis of this variation remains largely unknown, although host genetic factors seem to influence disease risk. In the first study presented in this thesis, it was shown that IL-2 plays a crucial role in human immunity against dermotropic Leishmania species. It was observed that the transcripts of several genes of the IL-2 pathway were more abundant in skin ulcers caused by Leishmania braziliensis than in normal skin samples. A primary association study on Brazilians (754 individuals from 209 families) identified two polymorphisms in the IL2RA gene associated with CL caused by L. braziliensis [rs10905669 (p = 3x10-4) and rs706778 (p = 3x10-4)]...

Avaliação do potencial terapêutico de membranas de celulose bacteriana contendo dietilditiocarbonato (DECT)na infecção experimental por L. brasilienses / Evaluation of the therapeutic potential of diethyldithiocarbonate-containing bacterial cellulose membranes (DECT) in experimental infection by L. brasilienses

A leishmaniose continua sendo um problema de saúde pública mundial. As opções terapêuticas limitadas, a toxicidade dos fármacos disponíveis e os relatos de resistência reforçam a necessidade do desenvolvimento de novas opções terapêuticas. Neste contexto, nós demonstramos previamente que o dietilditiocarbamato (DETC), um inibidor da enzima superóxido dismutase1 (SOD1), pode diminuir a infecção por L. braziliensis, in vivo. Neste trabalho, nós testamos o DETC numa formulação tópica empregando membranas de celulose bacteriana (BC-DETC). O tratamento de macrófagos murinos infectados por Leishmania com BC-DETC resultou na morte dos parasitas intracelulares de forma direta e dose-dependente, sem evidência de efeito tóxico para as células hospedeiras. A morte parasitária, in vitro, foi associada com a diminuição da atividade da SOD1, em paralelo com o aumento da produção de superóxido e decitocinas pró-inflamatórias. A eficácia de BC-DETC, in vivo, foi demonstrada em camundongos BALB/c infectados com L. braziliensis. A aplicação tópica de BC-DETC à lesão cutânea diminuiu significativamente a úlcera na orelha e a carga parasitária no sítio de infecção. Adicionalmente, a resposta inflamatória, avaliada pela expressão de IFN-γ e TNF-α, foi suprimida in situ, bem como na resposta de memória (recall) usando células do linfonodo drenante. Finalmente, BC-DETC foi capaz de reduzir a carga parasitária em macrófagos humanos, um efeito que foi revertido na presença de antioxidante. Conjuntamente, estes resultados apontam para a viabilidade do uso de BC-DETC como uma nova formulação para a quimioterapia da leishmaniose cutânea causada por L. braziliensis.

Leishmaniasis remains a worldwide public health problem. The limited therapeutic options, drug toxicity and reports of resistance reinforce the need for the development of new treatment options. Among these options, we previously showed that diethyldithiocarbamate (DETC), a superoxide dismutase 1 inhibitor (SOD1), can decrease L. braziliensis infection, in vivo. Herein, we tested DETC in a topical formulation employing bacterial cellulose membranes (BC-DETC). Treatment of leishmania-infected murine macrophages with BC-DETC resulted in a direct and dose-dependent killing of intracellular parasites, without pronounced toxic effects to host cells. In vitro parasite killing was associated with decreased SOD1 activity paralleled by increased superoxide and pro inflammatory cytokine production. In vivo efficacy of BC-DETC was then demonstrated in L. braziliensis-infected BALB/c mice. Topical application of BC-DETC to dermal lesions significantly decreased ear thickness and parasite load at the infection site. Additionally, the inflammatory response, namely expression of IFN-γ and TNF-α, was down modulated in situ as well as in recall responses employing draining lymph node cells. Finally, BC-DETC was also capable of decreasing parasite load within human macrophages, an effect that was reversed in the presence of anti-oxidants. Collectively, these results point to the feasibility of using BC-DETC as a new topical formulation for the chemoprophylaxis of cutaneous leishmaniasis caused by L. braziliensis.

Comparative analysis of the tissue inflammatory response in human cutaneous and disseminated leishmaniasis

Cutaneous leishmaniasis (CL) is the most frequent clinical form of tegumentary leishmaniasis and is characterised by a single or a few ulcerated skin lesions that may disseminate into multiple ulcers and papules, which characterise disseminated leishmaniasis (DL). In this study, cells were quantified using immunohistochemistry and haematoxylin and eosin staining (CD4+, CD68+, CD20+, plasma cells and neutrophils) and histopathology was used to determine the level of inflammation in biopsies from patients with early CL, late CL and DL (ulcers and papules). The histopathology showed differences in the epidermis between the papules and ulcers from DL. An analysis of the cells present in the tissues showed similarities between the ulcers from localised CL (LCL) and DL. The papules had fewer CD4+ T cells than the DL ulcers. Although both CD4+ cells and macrophages contribute to inflammation in early CL, macrophages are the primary cell type associated with inflammation intensity in late ulcers. The higher frequency of CD20+ cells and plasma cells in lesions demonstrates the importance of B cells in the pathogenesis of leishmaniasis. The number of neutrophils was the same in all of the analysed groups. A comparison between the ulcers from LCL and DL and the early ulcers and papules shows that few differences between these two clinical forms can be distinguished by observing only the tissue.

Decreased memory T-cell response and function in human immunodeficiency virus-infected patients with tegumentary leishmaniasis

The effects of human immunodeficiency virus (HIV) on the immune response in patients with cutaneous leishmaniasis have not yet been fully delineated. This study quantified and evaluated the function of memory T-cell subsets in response to soluble Leishmania antigens (SLA) from patients coinfected with HIV and Leishmania with tegumentary leishmaniasis (TL). Eight TL/HIV coinfected subjects and 10 HIV seronegative subjects with TL were evaluated. The proliferative response of CD4+and CD8+T-cells and naïve, central memory (CM) and effector memory (EM) CD4+T-cells in response to SLA were quantified using flow cytometry. The median cell division indices for CD4+and CD8+T-cells of coinfected patients in response to SLA were significantly lower than those in patients with Leishmania monoinfection (p < 0.05). The proportions of CM and EM CD4+T-cells in response to SLA were similar between the coinfected patients and patients with Leishmania monoinfection. However, the median CM and EM CD4+T-cell counts from coinfected patients were significantly lower (p < 0.05). The reduction in the lymphoproliferative response to Leishmania antigens coincides with the decrease in the absolute numbers of both EM and CM CD4+T-cells in response to Leishmania antigens in patients coinfected with HIV/Leishmania.

American tegumentary leishmaniasis: correlations among immunological, histopathological and clinical parameters

BACKGROUND: American tegumentary leishmaniasis has an annual incidence of 1 to 1.5 million cases. In some cases, the patient's immune response can eliminate the parasite, and the lesion spontaneously resolves. However, when this does not occur, patients develop the disseminated form of the disease. OBJECTIVE: To investigate the association between clinical, laboratory and pathological findings in cases of American tegumentary leishmaniasis. METHODS: A retrospective study of the medical records of 47 patients with American cutaneous leishmaniasis. Clinical, laboratory and epidemiological data were collected, and semi-quantitative histopathological analyses were performed using the Spearman correlation coefficient (p <0.05). RESULTS: Mean patient age was 40.5 years. A total of 29.7% individuals were female and 70.2% were male, and 40.4% of the patients were farmers. The ulcerative form was found in 53.2% of patients, of whom 59.6% had lesions in the limbs. The average time to diagnosis was 22.3 months. The following positive correlations were significant: age and duration of the disease, Montenegro reaction, degree of granulomatous transformation and epithelioid cell count; duration of disease, Montenegro reaction and number of lymphocytes; epithelial hyperplasia and edema, hemorrhaging, and epithelial aggression; number of plasmocytes and number of parasites. The main negative correlations found were as follows: age and serology; time and parasite load; epithelial hyperplasia and degree of granulomatous transformation. CONCLUSION: The long duration of the disease could be explained by the fact that lesions were relatively asymptomatic, and therefore ignored by patients with low literacy levels. Individuals may have simply waited for spontaneous healing, which proved to be dependent on the activation of hypersensitivity mechanisms. .

Avaliação da capacidade protetora de antígenos recombinantes contra a Leishmaniose Tegumentar / Protective capacity of recombinant antigens against tegumentary leishmaniasis

A leishmaniose é uma doença de escala global, que afeta 12 milhões de pessoas e pode causar um espectro de doenças que vai desde a forma cutânea localizada, que tende para a cura espontânea, até a forma visceral que é fatal. Apesar da gravidade da doença, até o momento não existe uma vacina efetiva para prevenir a leishmaniose. Dentre os antígenos promissores para o desenvolvimento de uma vacina, destacam-se as proteínas ribossomais (S4, S6, L3 e L5) e a KMP-11, uma proteína de superfície presente nos membros da família tripanosomatidae. Nosso estudo consistiu em avaliar os efeitos da imunização com estes antígenos frente ao desafio com L. major e com L. braziliensis, empregando modelos experimentais de infecção. Primeiramente, avaliamos a capacidade protetora dos antígenos ribossomais frente à infecção por L. major. Dos quatro antígenos avaliados, apenas L3 ou L5 foram capazes de prevenir o desenvolvimento da lesão e de diminuir a carga parasitária. A vacinação de camundongos com estes antígenos, na presença de CpG, induziu um perfil de resposta Th1, com elevada produção de IFN-γ, baixa produção de IL-10 e presença de anticorpos IgG2a. Em seguida, avaliamos a capacidade protetora dos antígenos L3 e L5...

Leishmaniasis is a global disease affecting 12 million people and can cause diseases that range from self-healing localized cutaneous leishmaniasis to fatal visceral leishmaniasis. Despite the severity of the disease, there is no effective vaccine to prevent leishmaniasis. Among the promising antigens for the development of a vaccine, stand out the ribosomal proteins (S4, S6, L3, and L5) and KMP-11, a surface protein, widely found in the members of family Trypanosomatidae. Our study evaluated the effects of immunization with these antigens upon challenge with L. major and L. braziliensis, employing the experimental models of infection. First, we evaluated the protective ability of ribosomal antigens to infection by L. major. Among the four antigens examined only L3 or L5...

Expressão gênica associada à produção de IFNG na resposta inicial à Leishmania braziliensis / Gene expression associated to IFNG production at initial response to infection with Leishmania braziliensis

Células de voluntários saudáveis, expostas in vitro a Leishmania, podem produzir altos níveis de IFNG na primeira exposição ao parasita, caracterizando os indivíduos como alto respondedores (AR), ou baixos níveis de IFNG, caracterizando os indivíduos baixo respondedores (BR). O objetivo deste estudo foi estudar o perfil de expressão gênica associado ao padrão de produção de IFNG de indivíduos AR e BR. Também avaliamos se as assinaturas gênicas identificadas nos indivíduos AR e BR se associam com o padrão de resposta imune observado em indivíduos de área endêmica identificada como subclínicos (SC) ou portadores de Leishmaniose Cutânea Localizada (LC). Inicialmente, Células Mononucleares do Sangue Periférico (CMSP) de voluntários saudáveis foram estimuladas in vitro com Leishmania braziliensis e identificamos indivíduos AR (com produção de IFNG acima de 330 pg/ml)...

Naïve volunteers exposed to Leishmania in vitro can be high IFNG producers, characterizing a high-responder (HR), or low IFNG producers, characterizing a low-responder (LR). The purpose of this work is to characterize the gene expression profile associated to IFNG production in HR and LR individuals. Formerly, we analyzed if the gene signature identified could be associated with the pattern of immune response in individuals from endemic areas identified as subclinical (SC), or patients with Localized Cutaneous Leishmaniasis (LC). Initially, we stimulated Peripheral Blood Mononuclear Cells (PBMCs) from healthy volunteers in vitro with Leishmania braziliensis where we identified HR (IFNG production above 330 pg/ml)...

CD8+ T cells in situ in different clinical forms of human cutaneous leishmaniasis

Introduction Leishmania braziliensis infection induces a large spectrum of lesions that clinically manifest as nodules or papules that progress to ulcers. Although it is already known that T helper cells predominate in the lesions, cytotoxic T cells have also been reported to be present, and their role in leishmaniasis immunopathogenesis is not well known. This study investigated the amounts of CD8+ and granzyme B+ cells in different clinical forms of human cutaneous leishmaniasis (CL). Methods Forty tissue fragments from early (E-CL) and late CL (L-CL) lesions and from disseminated leishmaniasis (DL) - papules and ulcers - were characterized. The inflamed area per fragment was calculated, and the CD8 and granzyme B expression levels in the infiltrates were quantified by counting positive cells in 15 fields. The localization of CD8 and granzyme B was graded subjectively. Results Inflammation was higher in L-CL and DL ulcers. CD8 expression was increased in late ulcerated lesions compared to recent lesions. The increase in CD8+ cells also correlated with the duration of the lesion. Papules had a higher frequency of granzyme B+ cells than E-CL lesions, although the frequency was similar to those for late and DL ulcers. CD8+ cells were mostly found in the papillary dermis. Conclusions CD8+ T and granzyme B+ cells are present in the inflammatory infiltrates of CL and DL and may participate in the immunopathogenesis of Leishmania infection. .

Chemokines and chemokine receptors expression in the lesions of patients with American cutaneous leishmaniasis

American cutaneous leishmaniasis (ACL) presents distinct active clinical forms with different grades of severity, known as localised (LCL), intermediate (ICL) and diffuse (DCL) cutaneous leishmaniasis. LCL and DCL are associated with a polarised T-helper (Th)1 and Th2 immune response, respectively, whereas ICL, or chronic cutaneous leishmaniasis, is associated with an exacerbated immune response and a mixed cytokine expression profile. Chemokines and chemokine receptors are involved in cellular migration and are critical in the inflammatory response. Therefore, we evaluated the expression of the chemokines CXCL10, CCL4, CCL8, CCL11 and CXCL8 and the chemokine receptors CCR3, CXCR3, CCR5 and CCR7 in the lesions of patients with different clinical forms of ACL using immunohistochemistry. LCL patients exhibited a high density of CXCL10+, CCL4+ and CCL8+ cells, indicating an important role for these chemokines in the local Th1 immune response and the migration of CXCR3+ cells. LCL patients showed a higher density of CCR7+ cells than ICL or DCL patients, suggesting major dendritic cell (DC) migration to lymph nodes. Furthermore, DCL was associated with low expression levels of Th1-associated chemokines and CCL11+ epidermal DCs, which contribute to the recruitment of CCR3+ cells. Our findings also suggest an important role for epidermal cells in the induction of skin immune responses through the production of chemokines, such as CXCL10, by keratinocytes.